Methyl 4-oxo-5-tetradecynoate is a compound represented by formula: ##STR1## and is an important intermediate for synthesizing (R,Z)-5-dec-1-enyloxacyclopentan-2-one, which is a sex pheromone of Japanese beetles (Popillia japonica) having done much harm in U.S.A. and has been used as an attractant for Japanese beetles. As shown by Reaction Scheme I, (R,Z)-5-dec-1-enyloxacyclopentan-2-one (4) can be obtained by asymmetrically reducing methyl 4-oxo-5-tetradecynoate (1) to convert it to the corresponding alcohol (2), subjecting the alcohol (2) to hydrolysis and cyclization to form a lactone (3), and partially reducing the lactone (3). ##STR2##
Conventionally known processes for preparing methyl 4-oxo-5-tetradecynoate include (a) the process of R. Baker et al., J. Chem. Soc., Perkin I, 69 (1982), (b) the process of M. M. Midland et al., J. Org. Cem., Vol. 46, 4108 (1981), and (c) the process of S. Senda et al., Argric. Biol. Chem., Vol. 47, 2595 (1983) as illustrated below. ##STR3##
The processes (a) and (b) attain very low yields of the compound (1). The process (c), though achieving relatively high yields, encounters difficulty in separation of by-products, failing to obtain the compound (4) at high purity. Moreover, all of these conventional processes entail extremely high cost of production. More specifically, any of them uses an expensive acid chloride. In particular, the process (b) needs expensive lithium compounds, e.g., n-butyl lithium, and the process (c) also requires lithium compounds and chlorotrimethylsilane.